scholarly journals MITIGATION OF AUTOGENOUS SHRINKAGE OF HIGH-STRENGTH CONCRETE USING PRE-WETTED ARTIFICIAL LIGHTWEIGHT FINE AGGREGATE

2014 ◽  
Vol 79 (695) ◽  
pp. 19-26
Author(s):  
Shusuke KUROIWA ◽  
Hiroshi JINNAI ◽  
Satoru NAMIKI ◽  
Toyoharu NAWA
Keyword(s):  
High Strength Concrete ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Fine Aggregate ◽  
Strength Concrete

scholarly journals Life-Cycle Assessment of High-Strength Concrete Mixtures with Copper Slag as Sand Replacement

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Aysegul Petek Gursel ◽  
Claudia Ostertag
Keyword(s):  
Life Cycle ◽  
Environmental Impacts ◽  
High Strength Concrete ◽  
High Strength ◽  
Copper Slag ◽  
Embodied Energy ◽  
Fine Aggregate ◽  
Natural Sand ◽  
Strength Concrete ◽  
Concrete Mixtures

Aggregate consumption rates have now exceeded natural renewal rates, signaling shortages both locally and globally. Even more concerning is that the worldwide markets for construction aggregates are projected to grow at an annual rate of 5.2% in the near future. This increase is attributed to rapid population growth coupled with the economic development worldwide. In terms of material availability, one of the most vulnerable regions is the Asia-Pacific region specifically, Singapore, where there is higher demand but limited availability of natural sand and gravel for use as aggregates in concrete construction projects. This paper focuses mainly on the environmental impacts of fine aggregate alternatives used in high-strength concrete applications in Singapore, which is one of the major global importers of natural sand following China. Singapore has been experiencing political and environmental challenges linked to the shortage of natural sand use as aggregates, even while the demand is increasing in the construction sector. Copper slag, a readily available waste material from shipyards in Singapore, is a possible replacement material for a portion of the natural sand in concrete mixtures, thus sustaining the projected growth in the region. A life-cycle assessment approach is applied to investigate the environmental impacts of copper slag and its alternative use as natural sand in high-strength concrete applications in Singapore. The system boundary consists of the major production processes of concrete constituents (including Portland cement and fine and coarse aggregates, with CS considered as fine aggregate) from a cradle-to-gate perspective, consisting of relevant life-cycle phases of raw materials extraction, transportation, and production processes at the relevant facility where the production occurs. Output from the assessment is provided in terms of embodied energy use and air emissions of concrete mixes with varying percentages of copper slag as fine aggregate. Results show that environmental impacts of aggregates decrease with the increasing substitution rate of natural sand with copper slag when calculated on the basis per unit volume of the concrete mix. For example, 40% and 100% sand replacements with copper slag result in a reduction of 8% and 40% in embodied energy, 12% and 30% in global warming potential, 8% and 41% in acidification, and 7% and 35% in particulate matter formation, respectively. Normalized impacts (i.e., normalized with respect to compressive strength) are observed to remain at almost similar levels for concrete mixes with up to 40% natural sand having been replaced with copper slag. Therefore, it is recommended that replacement of fine aggregates by 40–50% of copper slag (by weight) will produce concrete mixtures with comparable environmental impacts while maintaining feasible durability and strength properties.

Engineering Characteristics of Concrete Made of Desert Sand from Maowusu Sandy Land

2012 ◽  
Vol 174-177 ◽  
pp. 604-607 ◽  
Author(s):  
Bao Hong Jin ◽  
Jian Xia Song ◽  
Hai Feng Liu
Keyword(s):  
High Strength Concrete ◽  
Civil Engineering ◽  
High Strength ◽  
Fine Aggregate ◽  
Sandy Land ◽  
Strength Concrete ◽  
Engineering Characteristics ◽  
Desert Sand ◽  
Fine Grain ◽  
Engineering Requirement

The desert sand from Maowusu sandy land is very fine aggregate. Currently, there are no national specifications concerning the application of desert sand with very fine grain. To apply the desert sand to concrete in civil engineering, concrete specimens made of the desert sand had been tested in order to clarify its engineering characteristics. On the basis of determined chemical composition and physical characteristics of the desert sand, the mechanical properties of concrete made of fine aggregate from Maowusu sandy land were investigated. The results of the tests indicated that the desert sand could be used as a fine aggregate in concrete for general civil engineering. At the same time, the desert sand was used to confect high strength concrete, the strength and workability of which met general engineering requirement, which provided references for high strength concrete preparation in these regions

scholarly journals Strength Determination of High Strength Concrete Blended with Copper Slag and Fly Ash

2021 ◽  
Vol 9 (VII) ◽  
pp. 1198-1203
Author(s):  
Jamshed Alam
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Free Water ◽  
High Strength ◽  
Copper Slag ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Strength Concrete ◽  
Free Water Content

An experimental analysis was conducted to study the effects of using copper slag as a fine aggregate (FA) and the effect of fly ash as partial replacement of cement on the properties high strength concrete. In this analysis total ten concrete mixtures were prepared, out of which five mixes containing different proportions of copper slag ranging from 0% (for the control mix) to 75% were prepared and remaining five mixes containing fly ash as partial replacement of cement ranging from 6% to 30% (all mixes contains 50% copper slag as sand replacements). Concrete matrix were tested for compressive strength, tensile strength and flexural strength tests. Addition of copper slag as sand replacement up to 50% yielded comparable strength with that of the control matrix. However, further additions of copper slag, caused reduction in strength due to an increment of the free water content in the mix. Concrete mix with 75% copper slag replacement gave the lowest compressive strength value of approximately 80 MPa at 28 days curing period, which is almost 4% more than the strength of the control mix. For this concrete containing 50% copper slag, fly ash is introduced in the concrete to achieve the better compressive, split and flexural strengths. It was also observed that, introduction of the fly ash gave better results than concrete containing 50% copper slag. When concrete prepared with 18 % of fly ash, the strength has increased approximately 4%, and strength decreased with further replacements of the cement with fly ash. Hence, it is suggested that 50% of copper slag can be used as replacement of sand and 18% fly ash can be used as replacement of cement in order to obtain high strength concrete.

scholarly journals Lightweight high-strength concrete with the use of waste cenosphere as fine aggregate

2019 ◽  
Vol 24 (4) ◽  
Author(s):  
Felipe Basquiroto de Souza ◽  
Oscar Rubem Klegues Montedo ◽  
Rosielen Leopoldo Grassi ◽  
Elaine Gugliemi Pavei Antunes
Keyword(s):  
High Strength Concrete ◽  
Power Plants ◽  
Lightweight Concrete ◽  
Construction Materials ◽  
Hollow Structure ◽  
High Strength ◽  
Cementitious Materials ◽  
Partial Substitution ◽  
Fine Aggregate ◽  
Strength Concrete

ABSTRACT Cenosphere is a coal combustion by-product that presents interesting properties to be used in the production of cementitious materials, such as hollow structure, low density, low thermal conductivity and notably thermal stability. In addition, it displays pozzolanic reactivity under thermal curing. However, the cenosphere potential for the development of unique construction materials has not been fully investigated, remaining obscure for both power plants and the construction field. This study investigated the employment of waste cenosphere in partial substitution to sand for the obtainment of high-strength lightweight concrete materials. Cenosphere from a Brazilian power plant was chemically and physically characterized and the feasibility of its use in concretes was investigated. It was discovered that the power plant’s fly ash is composed of approximately 0.2% of cenosphere. In addition, the cenosphere displayed size ranging from 30 to 300 µm and were suitable for use as fine aggregate in concrete. Concrete with 33, 67, and 100% fine aggregate replacement by the waste cenosphere was produced. Cenosphere-based high strength concrete presented strength higher than 70 MPa and density as low as 1500 kg • m-3. Compared to mixes of reference, cenosphere application as fine aggregate improved the specific strength of high-strength concrete while maintaining equivalent mechanical properties.

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